Method for impregnating carbonaceous material



Patented Mar. 5, 1935 UNITED STATES METHOD FOR PATENT owls]:

DWPRE GNATING OARBONA- CEOUS MATERIAL No Drawing. Application December 13, 1932, Serial No. 646,979

13 Claims.

This invention relates toa method for impregnating carbonaceous material.

More particularly, the method in accordance with this invention finds advantage in the preparation of carbonaceous materials, and. more particularly, of low density carbonaceous materials for use, in the production of dynamites and, more particularly, in the production of dynamites of high cartridge count.

Heretofore in the production of dynamites,

and more particularly of the type including ammonium nitrate, sodium nitrate and carbonaceous material as ingredients, it has been customary to impregnatethe carbonaceous material with more or less of the ammonium and/or, 'sodium nitrate, such having been found to enable the production of dynamites of high cartridge count by enabling the use of a low density carbonaceous material, the absorptive capacity of which is reduced by the impregnation, thus avoiding absorption of the sensitizer, as nitroglycerin, usually included in such dynamites, with loss of sensitivity.

Heretofore carbonaceous materials for use in the production of dynamites have been impregnated with, for example, more or less of the ammonium nitrate constituent of the dynamite through the medium of an aqueous solution of ammonium nitrate with subsequent elimination of water by heating. Such process is, however, dangerous from the temperature and time required to remove the water.

Again, carbonaceous materials have beenimpregnated with, for example, ammonium nitrate through the medium of a fusion of ammonium nitrate and a salt containing water of crystallization with subsequent cooling. Such process is, however, not ideal, due to the presence of a salt containing water of crystallization in the product, which reduces the amount of am monium nitrate and cuts strength and increases hygroscopicity.

Now in" accordance with this invention it has taining ammonium nitrate, and maintained at a suitable temperature for absorption by the nitrate or liquefaction under pressure. The ammonium nitrate will be liquefied with liquefaction of ammonia by absorption of ammonia by 5 the nitrate or under pressure, if pressure be used.

Thecarbonaceous material to be impregnated, such, for example, as. sawdust, balsa wood, bagasse fibre, etc., or the like, is introduced into the solution formed and saturated there- 10 with, though it may be introduced originally with the ammonium nitrate. The temperature is then raised sulficiently to drive olT the ammonia as a gas, with or without reduction in pressure, leaving the carbonaceous material im- 15 pregnated with crystallized ammonium nitrate.

The procedure involving the method in accordance with this invention may be carried out in any suitable form of apparatus, it being only necessary to provide a vessel suitable for containing ammonium nitrate and carbonaceous material to be impregnated and provided with means for cooling and heating, as, for example, a jacket through which, for example, brine may be circulated for cooling and through which, for example, hot water or steam may be circulated for heating. The vessel will, of course, be provided with an inlet and an outlet for ammonia gas, and where pressure is used will be capable of withstanding pressure required for liquefaction of ammonia gas under the temperature of operation.

As more specifically illustrative of the practical adaptation of the method in accordance with this invention, for example, 177 grams of ammonium nitrate are charged into a vessel such as generally described above and which may, for example, be a Baker-Perkins smokeless powder mixer equipped with a jacket on its bot-- tom for the circulation of heating and cooling mediums. After the ammoniumgnitrate is charged into the mixer the temperature is lowered to say about 0 C. by circulating ice water or cooled brine through the jacket on the bot tom of the mixer. Ammonia gas is then passed through the mixer at atmospheric pressure for say about one hour at the rate of about 6% liters per minute. At the end of the period of one hour the ammonium nitrate in the mixer will be liquefied and then about 50 grams of carbonaceous material, as for example, balsa wood, are added and mixedwvith the liquefied ammonium nitrate, for example, by means of the mixing device with which the Baker-Perkins mixer is provided. The mixing is continued for about 45 minutes and desirably during the mixing a current of ammonia gas at the rate of about 2 liters per minute is passed through themixer. During the mixing period the temperature should be maintained within say about the range 3-5 C.' When the liquefied ammonium nitrate. and balsa wood are thoroughly admixed, the admission of ammonia gas is stopped and steam at about 100 C. is circulated through the jacket for a period of say about minutes. The steam will cause the ammonia to be driven 01f as a gas, in which form it is withdrawn from the mixer,'and the ammoniunf nitrate impregnated into the balsa wood will solidify.

The product on removal from the mixer will be found to comprise balsa wood impregnated with ammonium nitrate and on analysis will be found to contain less than 1% of moisture.

The product produced in accordance with the method embodying this invention, as has been indicated, lends itself advantageously for use in the production of dynamites. Thus, by way of illustration, for example, a dynamite may be prepared using carbonaceous material impregnated with ammonium nitrate as described in the above example, on the following formula:

Per cent Nitroglycerin 9 Nitroglycol 3 Granular ammonium nitrate 15 Sodium nitrate 5 Carbonacedus material prepared as above 68 The dynamite,made up on the above formula will be found to be entirely satisfactory, having a rate of detonation of about 2100 meters per second and a sensitiveness of about 16 inches. The dynamite will be characterized by high cartridge count and will be found to have a cartridge count of about 580 standard 1% x 8" cartridges per pounds of dynamite.

As illustrative of procedure in accordance with by circulating brine through the jacket of the vessel. The pressure will cause the ammonia to liquefy at the temperature existing and the liquid ammonia will combine with the ammonium nitrate to form NH4NO3.2NH:. The amount of ammonia required to dissolve the 312 pounds of ammonium nitrate will consequently be 132.5 pounds plus the amount in gaseous form required to maintain the pressure.

When solution of the ammonium nitrate has been completed the release valve is opened and when normal pressure is reached 90 pounds of carbonaceous material, as sawdust, are introduced into the vessel and mixed with the solution for about ten minutes. The vessel is then heated to say 100 F. by passing hot water or low pressure steam through the jacket and the pressure reduced, by exhausting the vessel into a pump, and the ammonia removed rapidly in gaseous form. As the ammonia is removed the ammonium nitrate will crystallize within the fibre of the carbonaceous material.

Alternatively, the ammonia may be introduced into the vessel at atmospheric pressure and the solution formed by absorption of the ammonia by the ammonium nitrate, such, however, will lengthen the time required for solution.

Again, the carbonaceous material may beintroduced into the vessel with the ammonium nitrate rather than after the solution is formed, but such procedure will lengthen the time since the presence of the carbonaceous material will make chilling morediflicult.

The impregnated carbonaceous material prepared by the method in accordance with this invention will have the advantage that it will be substantially anhydrous, since the liquefied ammonia gas, the solvent for the ammonium nitrate, will be anhydrous or substantially anhydrous. The method will be practiced with safety since the temperature necessary to drive off the ammonia from the solution of ammonium nitrate after impregnation into the carbonaceous material will be well within the limits of safety.

The process in accordance with this invention will be advantageous from the fact that it will be entirely safe in that the use of dangerously high temperature is not required, and in that the product will be of reduced hydroscopicity, will not' soften and set when exposed to high summer temperatures, and willhave maximum strength in that the ammonium nitrate will be free from admixture with other salts.

What I claim and desire to protect by Letters Patent is:

1. The method of impregnating carbonaceous material with ammonium nitrate which includes forming a solution comprising ammonium nitrate and liquid substantially anhydrous ammonia, impregnating carbonaceous material with the solution and removing ammonia from the carbonaceous material in the form of gas.

2. The method of impregnating carbonaceous material with ammonium nitrate which includes cooling ammonia gas in the presence of ammonium nitrate whereby a solution of ammonium nitrate in liquid ammonia is formed, admixing a carbonaceous material with the solution and heating sufiiciently to drive off ammonia in gaseous form.

3. The method of impregnating carbonaceous material with ammonium nitrate which includes cooling ammonia gas to about 0C. in the presence of ammonium nitrate whereby a solution of ammonium nitrate in liquid ammonia is formed, and iadmixing a carbonaceous material with the soluion.

4. The method of impregnating carbonaceous material with ammonium nitrate which includes cooling ammonia gas toabout 0 C. in the presnium nitrate whereby a solution of ammonium.

nitrate in liquid ammonia is formed, admixing wood sawdust with the solution and heating the wood sawdust sufizlciently to drive off ammonia in gaseous form.

6. The method of impregnating carbonaceous.

material with ammonium nitrate which includes cooling ammonia gas in the presence of ammonium nitrate whereby a solution of ammonium nitrate in liquid ammonia is formed,

ence (if-ammonium nitrate whereby a solution of incense balsa wood with the solution and heating the balsa wood sufllciently to drive off ammonia in gaseous form.

7. The method of impregnating carbonaceous material with ammonium nitrate which includes cooling ammonia gas in the presence of ammonium nitrate whereby a solution of ammonium nitrate in liquid ammonia is formed, admixing 'bagasse with the solution and heating the bagasse sumciently to drive ofi ammonia in gaseous form.

8. The method of impregnating carbonaceous material with ammonium nitrate which includes cooling ammonia gas in the presence of ammonium nitrate whereby a solution of ammonium nitrate in liquid ammonia is formed, admixing a carbonaceous material with the solution and removing ammonia from the carbonaceous material.

9. The method of impregnating carbonaceous material with ammonium nitrate which includes subjecting ammonia gas to superatmospheric pressure in the presence of ammonium nitrate whereby a solution of ammonium nitrate in liquid ammonia will be formed, admixing a carbonaceous material with the solution and removing ammonia from the carbonaceous material.

10. The method of impregnating carbonaceous material with ammonium nitrate which includes subjecting ammonia gas to a temperature of about 0 C. under a pressure of about five atmospheres in the presence of ammonium nitrate whereby a solution of ammonium nitrate in liquid ammonia is formed, admixing a carbonaceous material with the solution and removing ammonia from the carbonaceous material.

11. The method of impregnating carbonaceous material with ammonium nitrate which includes charging a closed vessel with ammonium nitrate, introducing ammonia gas into the vessel while maintaining a temperature and pressure within the vessel at which the ammonia gas will be liquefied for the formation of a solution of ammonium nitrate, admixing a carbonaceous material with the solution of ammonium nitrate in the vessel and removing ammonia from the carbonaceous material.

12. The method of impregnating carbonaceous material with ammonium nitrate which includes charging a closed vessel with ammonium nitrate, introducing ammonia gas into the vessel while maintaining a temperature and pressure within the vessel at which the ammonia gas will be liquefied for the formation of a solution of ammonium nitrate, admixing a carbonaceous material with the solution of ammonium nitrate in the vessel while continuing the introduction of ammonia gas in the vessel and finally removing ammonia from the carbonaceous material.

13. The method of impregnating carbonaceous material with ammonium nitrate which includes charging a closed vessel with ammonium nitrate and a carbonaceous material, introducing ammonia gas into the vessel while maintaining within the vessel 2. temperature and pressure such that a solution of ammonium nitrate in liquid ammonia will be formed and removing ammonia from carbonaceous material.

HUBERT H. CHAIVHPNEY. 

